Gas-cooking oven with oven scavenging means

ABSTRACT

A scavenging system for a gas oven whereby smoke and odors generated during normal baking operations or during a pyrolytic self-cleaning operation are entrained in an airflow passing through the cooking cavity, and they exit through an exhaust vent in the bottom wall of the oven liner and enter the gas flames of the bake burner where they are oxidized, and the air is combined with the flue gases to heat the oven. Deflector means are present in the firebox above the bake burner to act as an aspirator and create a suction for creating the airflow through the oven cavity. Other deflectors are positioned beneath the burner in association with air inlets in the bottom of the firebox to create a second suction that draws room air into the firebox so as to pass them into the gas flames to improve the efficiency of combustion.

1 United States Patent Inventor Raymond L. Dllls Louisville, Ky. 46,338

June 15, 1970 Nov. 30, 1971 General Electric Company Appl. No. Filed Patented Assignee GAS-COOKING OVEN WITH OVEN SCAVENGING MEANS 9 Claims, 3 Drawing Figs.

References Cited UNITED STATES PATENTS 4/1969 Perry 126/21 A 3,430,000 11/1969 Torreyetal. 3,530,847 9/1970 Myleretal ABSTRACT: A scavenging system for a gas oven whereby smoke and odors generated during normal baking operations or during a pyrolytic self-cleaning operation are entrained in an airflow passing through the cooking cavity, and they exit through an exhaust vent in the bottom wall of the oven liner and enter the gas flames of the bake burner where they are oxidized, and the air is combined with the flue gases to heat the oven. Deflector means are present in the firebox above the bake burner to act as an aspirator and create a suction for creating the airflow through the oven cavity. Other deflectors are positioned beneath the burner in association with air inlets in the bottom of the firebox to create a second suction that draws room air into the firebox so as to pass them into the gas flames to improve the efficiency of combustion.

GAS-COOKING OVEN WITH OVEN SCAVENGING MEANS BACKGROUND OF THE INVENTION Popular models of gas-cooking ovens are provided with walls forming a cooking cavity. A combustion chamber or firebox is located beneath the oven cavity and it is provided with a bake burner for generating hot flue gases for heading by convection. Large apertures are usually provided in the bottom portion of the oven cavity walls so that the hot flue gases may sweep through the cooking cavity. An oven vent is provided adjacent the top of the oven liner for carrying off the flue gases. This type of heading system is called a flow-through heating system. With the advent of high-temperature pyrolytic gas ovens for automatically cleaning the food soils and grease spatter from the walls forming the cooking cavity, another heading system has become popular; namely, the external heating system with the passage of hot flue gases through heating channels encircling the oven liner. Such an oven is called a muffle oven as is described in U.S. Pat. No. 3,364,9I2 of Raymond L. Bills and Bohdan I-Iurko. During both baking operations and high-temperature heat-cleaning operations, gaseous graduation products are formed within the oven cavity and means must be provided for treating these gaseous products before they are returned to the kitchen atmosphere. In the above Bills and I-Iurko patent a special smoke eliminator is installed in the oven exhaust vent in the top of the oven liner for incinerating the smoke, odors and other undesirable gaseous degradation products present in the oven effluent.

The principal object of the present invention is to provide a gas-cooking oven with a scavenging system for capturing the gaseous degradation products and passing them over the bake burner for obtaining complete oxidation, as well as providing preheated secondary air for the bake burner.

A further object of the present invention is to provide a gascooking oven with aspirator means for drawing oven aid over the burner for removing any gaseous degradation products from the air, and also drawing room air over the burner to improve the efficiency of combustion.

A further object of the present invention is to provide a pyrolytic-gas-cooking oven with an oven scavenging system for entraining the gaseous degradation products in a current of air that passes through the oven cavity, there being aspirator means in combination with the bake burner means for directing the oven exhaust over the bake burner for complete oxidation as well .as for drawing room air over the bake burner for improving the efficiency of combustion.

SUMMARY OF THE INVENTION The present invention, in accordance with one form thereof, relates to a pyrolytic-gas-cooking oven with external heating means in the form of convection currents of hot flue gases passing over the oven liner from a bake burner in a firebox beneath the oven liner. There is room air inlet means in the walls forming the cooking cavity and an oven exhaust means in the bottom wall of the oven liner. Deflector means are associated with the bake burner to draw the oven exhaust air into the firebox and over the bake burner so as to oxidize the oven smoke and odors entrained in the oven air.

BRIEF DESCRIPTION OF THE DRAWINGS My invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIG. 1 is a left side elevational view of the free-standing domestic gas range embodying the present invention with some parts broken away and others in cross section to show the heat flow pattern of a muffle oven, as well as to show the oven scavenging system of the present invention.

FIG. 2 is a fragmentary, cross-sectional elevational view taken on the line 2-2 of FIG. 1 at the bottom of the oven and particularly showing the deflector means associated with the bake burner means for aspirating both the oven air and the room air and passing them over the bake burner means before rising up the heading channels around the oven liner.

FIG. 3 is an elevational view on a reduced scale of the inside of the oven door to show the nature of the door gasket which is left open at the bottom to establish an air inlet means as part of the oven scavenging system. I

Turning now to a consideration of the drawings, and in particular to FIG. I, there is shown a freestanding domestic gas range 10 in left side elevational view comprising a horizontal cooktop 12 at waist height supporting a plurality of surface gas burners 14. Located therebeneath is an oven-cooking cavity 16 formed by a boxlike inner oven liner l8 and a front-opening oven door 20. A sheet metal outer cabinet or body struc ture 22 supports both the cooktop 12 and the oven liner I8. Arranged along the back of the cooktop 12 is a backsplash 24 which supports a control panel in the front face thereof and would be supplied with a complete array of oven burner control components 25. The gas control valves for the surface burners 14 are usually mounted along the front edge of the cooktop 12, as at 27.

The oven liner 18 has a bottom wall 29, opposite sidewalls 30, a top wall 31 and a rear wall 33. The bottom wall 29 of the oven liner is formed with a removable cover plate 35 so as to make it possible to gain easy access to a bake burner 37 which is located in a combustion chamber or firebox 39 beneath the bottom of the oven liner 18. The front of the oven liner 18 is open, and it has an outwardly turned flange 41 on its peripheral edge as part of the supporting means for the oven liner. Fastening means (not shown) such as adjustable J-bolts or the like are used at the rear of the oven to pull the oven liner 18 back into the oven body 22 until the flange 4I bears against a cooperating collar or front frame 43. Sandwiched between the flange 41 and the door frame 43 is a thermal break 45 such as a continuous asbestos or fiber glass gasket which serves to break the conductive path of the heat flow from the oven liner to the front of the oven body, as well as providing a sealing means between these two elements and preventing flue gases from escaping at the front of the oven.

The oven door 20 is fabricated of several sheet metal panels. It carries heavy thermal insulation (not shown) in its interior so as to retain most of the heat within the oven cavity 16 so that the temperature of the outer surface of the door will be within a comfortable temperature range so as not to cause discomfort or injury to those who might touch it during a high temperature heat-cleaning operation, as well as to prevent the wasteful loss of heat to the kitchen. The door 20 is shown with an outer door panel 47 of shallow pan shape and an inner door panel 48 of generally rectangular shallow pan shape that serves as a pluglike member that is inserted into the open front of the oven liner 18. This inner door panel 48 is supported from a larger inner door plate 50 by means not shown. The inner door panel 48 is separated from the inner door plate 50 and thermally isolated therefrom by means of a high-temperature beltlike gasket 52 such as woven asbestos or fiber glass or the like. This gasket 52 also serves to bear against the front flange 41 of the oven liner I8 and also engages the front frame 43 of the oven body 22 to substantially seal the front opening of the oven when the door is closed and locked (by locking means not shown). The door is adapted to be locked during the heat-cleaning cycle of operation. A handle for the door lock is shown at 55. Notice the extent of the door gasket 52 in FIG. 3 where the gasket stops short at the central part of the lower portion of the door. This creates a gap 53 which serves as an air inlet means to the cooking cavity 16. The upper edge of the oven door 20 is provided with a conventional door handle 54 of elongated shape which is held on the door by fastening screws 56 that are visible on the inner side of the door, as is best seen in FIG. 3.

Located within the oven body 22 and surrounding the inner oven liner I8, is an outer oven liner 60 that is spaced outwardly therefrom to form heating channels 62 encircling the inner oven liner. Vertically inclined baffles 64 are formed in the heating channel 62 at the two sides of the inner oven liner 18 such that more of the flue gases are directed forwardly to make up for the heat loss from the front of the oven and around the door. Then the gases pass through the top-heating channel 62 above the inner oven liner and then down the back side of the sidewalls 30 and across the backwall 33 where they enter the rear-heating channel 62 through vent openings 65 where the gases rise up the back of the oven and exhaust through a vent opening 67 beneath the backsplash 24. An air inlet opening 68 is formed in the backwall of the oven body, and a cooling channel 70 is formed to the rear of the heating channel 62 for mixing relatively cool room air with the flue gases before the gases are returned to the kitchen atmosphere. A layer of thermal insulation 71, such as fiber glass or the like, surrounds the bottom, top and two sides of the outer oven liner 60 for retaining the heat within the oven cavity. The air channel 70 at the back of the oven serves in place of thermal insulation behind the oven. Thus has been described a muffle oven design for externally heating the walls of the inner oven liner 18 both for normal baking operations as well as for hightemperature heat-cleaning operations.

The bake burner 37 may be of a size and a heat rating somewhere between 15,000 and 30,000 BTU's an hour for a standard discharge nozzle and gas pressure. The rear portion of the bake burner 37 has a venturi tube throat 73 provided with a gas line connector 74 through the backwall of the oven. A shroud 75 encircles the venturi and the gas line connector such that room air entering the air inlet 68 is also supplied as primary air to the venturi for mixture with the income gas fuel. An adjustable air mixer head (not shown) is combined with the venturi tube as is standard in this art in order to provide the best air-to-gas mixture ratio. The means for physically supporting the bake burner within the firebox, and the necessary pilot and gas line control valves are not shown, nor are the temperature sensing and control systems since they may be of standard construction and do not form part of the present invention.

Earlier the air inlet means 53 was described along the bottom edge of the oven door 20. This oven is quite different from the prior art because the escape means for this air is not in the top portion of the oven. Instead, the oven vent means is in the bottom wall of the inner oven liner 18 at 80 in the removable plate 35. It is best that this oven exhaust vent 80 is partially covered otherwise food soil or spillovers might fall through the opening and onto the bake burner 37. Thus, a raised shield 82 of generally elongated rectangular shape is centrally disposed on the cover plate 35 and extends from back to front of the oven. Beneath the shield 82 are formed converging support members 83, and the exhaust vent openings 80 are formed through each support member. An opening in the cover plate 35 is formed between the support members 83. Fastened to the underside of the cover plate 35 is a pair of symmetrical elongated V-shaped deflectors 85, 85 which form a central vertical duct 87 which overlies the burner 37 and communicates with the exhaust vent openings 80 thereby causing the exhaust to sweep over the top of the burner and over the side edges of the burner, and especially through the blue flames at 88 and 89. Thus, the deflectors 85, 85 in cooperation with the burner 37 act as an aspirator to create a suction and draw the oven air from the cooking cavity 16 and to ensure complete oxidation of the smoke, odors and vapors present in the gaseous degradation products. Similarly, a pair of oppositely disposed, symmetrical deflectors 90, 90 are positioned beneath the burner 37. These bottom deflectors 90, 90 are separated by a series of ambient air openings 92 which are centered beneath the burner in the bottom wall of the firebox 39. Additional air openings 94 are formed in the bottom of the oven body 22. These lower deflectors also serve as an aspirator of room air from beneath the oven to improve the efiiciency of combustion of the burner, and reduce the need for excess air to the burner.

Having described above the invention of a scavenging system for a gas-cooking muffle oven, it will readily be apparent to those skilled in this art that l have provided a scavenging system that also serves as a source of preheated secondary air for the bake burner. Moreover, I have reversed the normal flow pattern of oven air, and 1 am exhausting the gaseous degradation products through the bottom wall of the oven liner by using an aspirator means assembled around the lower bake burner. As this exhaust air passes over the burner, the smoke, odors and vapors will be completely oxidized before the exhaust passes with the hot flue gases up the heating channels that surround the inner oven liner.

Modifications of this invention will occur to those skilled in this art, therefore, it is to be understood that this invention is not limited to the particular embodiments disclosed, but that it is intended to cover all modifications which are within the true spirit and scope of this invention as claimed.

What is claimed as new and is desired to be secured by Letters Patent of the United States is:

l. A self-cleaning gas oven comprising an oven body supporting a boxlike oven liner and a front-opening access door which define an oven cooking cavity, a firebox located beneath the bottom wall of the oven liner, a bake burner means located within the firebox, heating channels extending from the firebox around the outside of the oven liner, an exhaust means from the heating channels so that convection currents of flue gases from the bake burner means may pass through the channels to heat the oven liner for raising the temperature within the oven cavity into a baking temperature range between about and 500 F. as well as into a heatcleaning temperature range that rises above 750 F an oven air inlet means adjacent the oven door, and an oven exhaust means in the bottom wall of the oven liner to be adjacent the bake burner means whereby an airflow entering the cooking cavity through the air inlet means serves first to entrain the smoke, odors and vapors in the oven atmosphere and exhausts them from the cooking cavity through the oven exhaust means so as to pass them over the bake burner means where they are oxidized, said scavenging airflow also serving as preheated secondary air for the bake burner means.

2. A self-cleaning gas oven as recited in claim 1 wherein the bake burner means extends longitudinally from back to front of the firebox, the said oven air inlet means being located adjacent the bottom edge of the oven door, and the oven exhaust means substantially overlying the said bake burner means, and deflector means associated with the oven exhaust means and the bake burner means to direct the scavenging airflow through the flames of the bake burner means before passing the air out of the firebox and into the heating channels.

3. A self-cleaning gas oven as recited in claim 2 wherein additional air inlet openings are formed in the firebox so that some room air may be furnished to the bake burner means as additional secondary air to support combustion.

4. A gas oven comprising an oven body supporting a boxlike inner oven liner and a front-opening access door which define an oven cooking cavity, and an outer oven liner surrounding the inner oven liner and spaced therefrom to form a firebox beneath the bottom wall of the inner oven liner as well as heating channels around the outside of the inner oven liner, a bake burner means located within the firebox to cause convection currents of flue gases to pass through the heating channels for heating the walls of the inner oven liner; the invention comprising room air inlet means in the walls fonning the cooking cavity, and an oven exhaust means in the bottom wall of the inner oven liner, and deflector means associated with the oven exhaust means to direct the oven exhaust air over the bake burner means so as to oxidize the oven smoke and odors entrained in the oven air before the oven air passes through the heating channels.

5. A gas oven as recited in claim 4 wherein the bake burner means is capable of raising the temperature of the oven cooking cavity to normal baking temperatures between about 140 and 550 F. as well as into a pyrolytic self-cleaning temperature range above normal baking temperatures for removing the food soils and grease spatter lodged on the inner surfaces of the walls forming the cooking cavity, and additional air inlet openings in the bottom portion of the firebox being in close relation with the bake burner means to direct incoming room air over the bottom portion of the burner as secondary air to support combustion.

6. A gas oven comprising an oven body supporting a boxlike oven liner and a front-opening access door which define an oven cooking cavity, a firebox positioned beneath the oven liner, bake burner means within the firebox, and heating channels surrounding at least a portion of the oven liner and being open to the firebox for carrying convection currents of flue gases into heat transfer relation with the oven liner and beyond for raising the oven temperature into the baking temperature range between about 140 and 550 F. as well as into a heat-cleaning temperature range above nonnal cooking temperatures for removing the accumulated food soils from the walls of the cooking cavity with the production of corresponding gaseous degradations products, and scavenger means for removing the degradation products from the cooking cavity, said scavenging means comprising air inlet means in at least one wall forming the cooking cavity and oven exhaust means in the bottom wall of the oven liner, and deflector means associated with the bake burner means and the oven exhaust means to create a suction that draws oven air from the cooking cavity and passes it into the gas flame to completely oxidize the gaseous degradation products so that they may pass with the flue gases through the heating channels and beyond.

7. A gas oven as recited in claim 6 wherein the said air let means is located adjacent the bottom edge of the oven door, and the oven exhaust means closely overlies the bake burner means, while the deflector means causes the air from the oven exhaust means' to be separated by the burner means into opposing flow patterns over the side edges of the burner means.

8. A gas oven as recited in claim 7 including second air inlet means fonned in the firebox, and second deflector means associated with the bake burner means and the said second air inlet means to create a suction that draws room air through the second air inlet means and passes it into the gas flames to improve the efficiency of combustion.

9. A gas oven as recited in claim 8 wherein the said second air inlet means closely underlies the bake burner means, while the said second deflector means causes room air from the second air inlet means to be separated by the burner means into opposing flow patterns over the side edges of the burner means. 

1. A self-cleaning gas oven comprising an oven body supporting a boxlike oven liner and a front-opening access door which define an oven cooking cavity, a firebox located beneath the bottom wall of the oven liner, a bake burner means located within the firebox, heating channels extending from the firebox around the outside of the oven liner, an exhaust means from the heating channels so that convection currents of flue gases from the bake burner means may pass through the channels to heat the oven liner for raising the temperature within the oven cavity into a baking temperature range between about 140* and 550* F. as well as into a heat-cleaning temperature range that rises above 750* F., an oven air inlet means adjacent the oven door, and an oven exhaust means in the bottom wall of the oven liner to be adjacent the bake burner means whereby an airflow entering the cooking cavity through the air inlet means serves fiRst to entrain the smoke, odors and vapors in the oven atmosphere and exhausts them from the cooking cavity through the oven exhaust means so as to pass them over the bake burner means where they are oxidized, said scavenging airflow also serving as preheated secondary air for the bake burner means.
 2. A self-cleaning gas oven as recited in claim 1 wherein the bake burner means extends longitudinally from back to front of the firebox, the said oven air inlet means being located adjacent the bottom edge of the oven door, and the oven exhaust means substantially overlying the said bake burner means, and deflector means associated with the oven exhaust means and the bake burner means to direct the scavenging airflow through the flames of the bake burner means before passing the air out of the firebox and into the heating channels.
 3. A self-cleaning gas oven as recited in claim 2 wherein additional air inlet openings are formed in the firebox so that some room air may be furnished to the bake burner means as additional secondary air to support combustion.
 4. A gas oven comprising an oven body supporting a boxlike inner oven liner and a front-opening access door which define an oven cooking cavity, and an outer oven liner surrounding the inner oven liner and spaced therefrom to form a firebox beneath the bottom wall of the inner oven liner as well as heating channels around the outside of the inner oven liner, a bake burner means located within the firebox to cause convection currents of flue gases to pass through the heating channels for heating the walls of the inner oven liner; the invention comprising room air inlet means in the walls forming the cooking cavity, and an oven exhaust means in the bottom wall of the inner oven liner, and deflector means associated with the oven exhaust means to direct the oven exhaust air over the bake burner means so as to oxidize the oven smoke and odors entrained in the oven air before the oven air passes through the heating channels.
 5. A gas oven as recited in claim 4 wherein the bake burner means is capable of raising the temperature of the oven cooking cavity to normal baking temperatures between about 140* and 550* F. as well as into a pyrolytic self-cleaning temperature range above normal baking temperatures for removing the food soils and grease spatter lodged on the inner surfaces of the walls forming the cooking cavity, and additional air inlet openings in the bottom portion of the firebox being in close relation with the bake burner means to direct incoming room air over the bottom portion of the burner as secondary air to support combustion.
 6. A gas oven comprising an oven body supporting a boxlike oven liner and a front-opening access door which define an oven cooking cavity, a firebox positioned beneath the oven liner, bake burner means within the firebox, and heating channels surrounding at least a portion of the oven liner and being open to the firebox for carrying convection currents of flue gases into heat transfer relation with the oven liner and beyond for raising the oven temperature into the baking temperature range between about 140* and 550* F. as well as into a heat-cleaning temperature range above normal cooking temperatures for removing the accumulated food soils from the walls of the cooking cavity with the production of corresponding gaseous degradatious products, and scavenger means for removing the degradation products from the cooking cavity, said scavenging means comprising air inlet means in at least one wall forming the cooking cavity and oven exhaust means in the bottom wall of the oven liner, and deflector means associated with the bake burner means and the oven exhaust means to create a suction that draws oven air from the cooking cavity and passes it into the gas flame to completely oxidize the gaseous degradation products so that they may pass with the flue gases through the heating channels and beyond.
 7. A gas oven as recited in claim 6 whereIn the said air inlet means is located adjacent the bottom edge of the oven door, and the oven exhaust means closely overlies the bake burner means, while the deflector means causes the air from the oven exhaust means to be separated by the burner means into opposing flow patterns over the side edges of the burner means.
 8. A gas oven as recited in claim 7 including second air inlet means formed in the firebox, and second deflector means associated with the bake burner means and the said second air inlet means to create a suction that draws room air through the second air inlet means and passes it into the gas flames to improve the efficiency of combustion.
 9. A gas oven as recited in claim 8 wherein the said second air inlet means closely underlies the bake burner means, while the said second deflector means causes room air from the second air inlet means to be separated by the burner means into opposing flow patterns over the side edges of the burner means. 